Netcatty/application/state/testSupport/localStorage.ts

/** Install isolated browser storage for hook tests, including Node without Web Storage. */
export function installTestLocalStorage(): () => void {
  const previous = Object.getOwnPropertyDescriptor(globalThis, 'localStorage');
  const values = new Map<string, string>();
  const storage: Storage = {
    get length() { return values.size; },
    clear: () => values.clear(),
    getItem: key => values.get(String(key)) ?? null,
    key: index => [...values.keys()][index] ?? null,
    removeItem: key => { values.delete(String(key)); },
    setItem: (key, value) => { values.set(String(key), String(value)); },
  };
  Object.defineProperty(globalThis, 'localStorage', { configurable: true, value: storage });
  return () => {
    if (previous) Object.defineProperty(globalThis, 'localStorage', previous);
    else Reflect.deleteProperty(globalThis, 'localStorage');
  };
}